improve panorama stitching

There are a few issues with the current panorama stitching process. One is that the images are not aligned properly, regardless of how many you've taken. Another problem is the appearance of black areas in some stitched images—especially in high-contrast scenes. It seems as though the panorama stitcher is trying to adjust the brightness of the images, even though they were all taken at the same shutter speed. I've attached an example (i made it much brighter) to highlight the issue of the black areas.